An unexpected disconnection occurred (?)

These problems could be caused by any number of things, including problems with your connection to a specific server. See if you are still disconnected when playing on Europe or Singapore, despite the higher latency. It'll help us narrow down where your individual problem is, as everyone will have separate issues. Running WinMTR can help diagnose the problem, and you may be able to contact your ISP about improving your connection to the servers.